Polylactic Acid (PLA): Difference between revisions
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[[File:Untitled design (2) (1).png|thumb|600x600px|The relative property levels of PLA.]]PLA (Polylactic Acid) is a commonly used thermoplastic filament in FDM 3D printing. It is recyclable, non-toxic, and the primary filament used by the MILL's processing team. | [[File:Untitled design (2) (1).png|thumb|600x600px|The relative property levels of PLA.]]PLA (Polylactic Acid) is a commonly used '''thermoplastic filament''' in FDM 3D printing. It is recyclable, non-toxic, and the primary filament used by the MILL's processing team. | ||
=== Specific Properties === | === Specific Properties === | ||
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=== On the Atomic Level === | === On the Atomic Level === | ||
Formula: (C<sub>3</sub>H<sub>4</sub>O<sub>2</sub>)<sub>n</sub> | |||
Synthesis: | |||
* Condensation of Lactic Acid (hence the name) with the loss of water. | |||
** '''Temperature control:''' Must be carried out '''below 200 °C'''; above that, lactide monomers will form due the increase in entropy.. | |||
** '''Reaction type:''' Condensation or esterification reaction. | |||
** '''Reversibility:''' Reaction is '''reversible''' and reaches equilibrium; therefore, '''water removal''' is necessary to drive polymerization (need the product side of the reaction to be favored. | |||
** '''Water removal methods:''' Apply '''vacuum''' or perform '''azeotropic distillation''' to shift equilibrium toward polymer formation. | |||
** '''Molecular weight:''' This method yields polymers up to '''~130 kDa''' initially. | |||
** '''Post-treatment:''' Crystallization from the melt concentrates reactive end groups (–COOH and –OH) in amorphous regions, allowing '''further chain growth'''. | |||
** '''Final result:''' Achieves '''high molecular weights (128–152 kDa)''' after solid-state polymerization. | |||
* Ring-opening polymerization of lactide with various metal catalyst in solution. | |||
** '''Temperature control:''' Polymerization generally occurs at '''130–180 °C''', which balances high conversion with minimal side reactions. | |||
** '''Reaction type:''' The '''ring-opening polymerization (ROP)''' of lactide is the '''primary industrial method''' for synthesizing high–molecular weight PLA. | |||
** '''Monomers used:''' Two key monomers produce PLA — '''lactic acid''' and the '''cyclic di-ester lactide'''. | |||
** '''Catalysts:''' Commonly uses metal catalysts like '''tin(II) ethylhexanoate''' for example. | |||
** '''Reaction medium:''' Typically carried out '''in solution''' or '''as a suspension'''. | |||
** '''Yield:''' The ROP route achieves high yields and '''molecular weights exceeding 100–200 kDa''', depending on catalyst efficiency and purification. | |||
** '''Drawback:''' The metal-catalyzed process can cause '''racemization''', lowering the '''stereoregularity''' and crystallinity of PLA relative to optically pure feedstocks (e.g., '''corn starch–derived lactic acid'''). | |||
[[File:PLA Reaction.jpg|thumb|The reaction formula for PLA through condensation of Lactic Acid or ring-opening polymerization of lactide.]] | |||
=== Prints === | === Prints === | ||
Revision as of 16:01, 27 October 2025
_(1).png)
PLA (Polylactic Acid) is a commonly used thermoplastic filament in FDM 3D printing. It is recyclable, non-toxic, and the primary filament used by the MILL's processing team.
Specific Properties
- Printing Temperature (oC): 190 - 220
- Hot bed Temperature (oC): 60
- Printing Speed (mm/s): 30 - 70
- Density (g/cm3): 1.21
- Bending Strength (MPa): 68 ± 2
On the Atomic Level
Formula: (C3H4O2)n
Synthesis:
- Condensation of Lactic Acid (hence the name) with the loss of water.
- Temperature control: Must be carried out below 200 °C; above that, lactide monomers will form due the increase in entropy..
- Reaction type: Condensation or esterification reaction.
- Reversibility: Reaction is reversible and reaches equilibrium; therefore, water removal is necessary to drive polymerization (need the product side of the reaction to be favored.
- Water removal methods: Apply vacuum or perform azeotropic distillation to shift equilibrium toward polymer formation.
- Molecular weight: This method yields polymers up to ~130 kDa initially.
- Post-treatment: Crystallization from the melt concentrates reactive end groups (–COOH and –OH) in amorphous regions, allowing further chain growth.
- Final result: Achieves high molecular weights (128–152 kDa) after solid-state polymerization.
- Ring-opening polymerization of lactide with various metal catalyst in solution.
- Temperature control: Polymerization generally occurs at 130–180 °C, which balances high conversion with minimal side reactions.
- Reaction type: The ring-opening polymerization (ROP) of lactide is the primary industrial method for synthesizing high–molecular weight PLA.
- Monomers used: Two key monomers produce PLA — lactic acid and the cyclic di-ester lactide.
- Catalysts: Commonly uses metal catalysts like tin(II) ethylhexanoate for example.
- Reaction medium: Typically carried out in solution or as a suspension.
- Yield: The ROP route achieves high yields and molecular weights exceeding 100–200 kDa, depending on catalyst efficiency and purification.
- Drawback: The metal-catalyzed process can cause racemization, lowering the stereoregularity and crystallinity of PLA relative to optically pure feedstocks (e.g., corn starch–derived lactic acid).
